合并两个有序链表

/*
struct ListNode {
    int val;
    struct ListNode *next;
    ListNode(int x) :
            val(x), next(NULL) {
    }
};*/
class Solution {
public:
    ListNode* Merge(ListNode* pHead1, ListNode* pHead2)
    {
        ListNode* newhead = new ListNode(-1);
        ListNode* temp = newhead;
        if(!pHead1) return pHead2;
        if(!pHead2) return pHead1;
        while(pHead1 && pHead2){
            if(pHead1->val <=pHead2->val){
                temp->next = pHead1;
                pHead1 = pHead1->next;
                temp = temp->next;
            }
            else{
                temp->next = pHead2;
                pHead2 = pHead2->next;
                temp = temp->next;
            }
        }
        if(!pHead1){
            temp->next = pHead2;
        }
        if(!pHead2){
            temp->next = pHead1;
        }
        return newhead->next;
    }
};

/*
struct ListNode {
    int val;
    struct ListNode *next;
    ListNode(int x) :
            val(x), next(NULL) {
    }
};*/
class Solution {
public:
    ListNode* Merge(ListNode* pHead1, ListNode* pHead2)
    {
        ListNode* head;
        if(!pHead1) return pHead2;
        if(!pHead2) return pHead1;
        if(pHead1->val <= pHead2->val){
            head=pHead1;
            head->next = Merge(pHead1->next,pHead2);
        }
        else{
            head = pHead2;
            head->next = Merge(pHead1,pHead2->next);
        }
        return head;
    }
};